Fix string integer parsing

[ianhi]

Fix for: #3356 by accepting floatish strings when we expect a string. As mentioned here: #3356 (comment) I ran into this in the wild being on some public data and latest zarr.

TODO:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.md
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)

[codecov]

Codecov Report

❌ Patch coverage is 76.92308% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.25%. Comparing base (48e7f4d) to head (5010159).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/zarr/core/dtype/npy/common.py	70.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3489      +/-   ##
==========================================
+ Coverage   61.21%   61.25%   +0.04%     
==========================================
  Files          84       84              
  Lines        9923     9949      +26     
==========================================
+ Hits         6074     6094      +20     
- Misses       3849     3855       +6     

Files with missing lines	Coverage Δ
src/zarr/core/dtype/npy/float.py	47.36% <100.00%> (+2.31%)	⬆️
src/zarr/core/dtype/npy/int.py	53.58% <100.00%> (+0.29%)	⬆️
src/zarr/core/dtype/npy/common.py	61.71% <70.00%> (+1.53%)	⬆️

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[d-v-b]

thanks @ianhi !